Hum. Reprod. Advance Access published online on June 28, 2007
Human Reproduction, doi:10.1093/humrep/dem188
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Predicting negligence in female sterilization failure using time interval to sterilization failure: analysis of 131 cases
Obstetrics and Gynaecology, 2nd Floor, Birmingham Women's Hospital, Birmingham B15 2TG, UK
1 Correspondence address. Tel: +44 121 607 4751; Fax: +44 121 607 4795; E-mail: r.varma{at}bham.ac.uk
BACKGROUND: Sterilization failure due to tubal non-occlusion or wrong structure sterilization is considered negligent, whereas spontaneous tubal recanalization or fistula formation is considered non-negligent. We examined whether interval to pregnancy failure was predictive of a negligent rather non-negligent failure mechanism. We aim to test this hypothesis in a selected population series of known mechanisms of sterilization failure and their time interval to failure.
METHODS: Analyses of 131 failed sterilizations pooled from UK (NHS Litigation Authority, Medical Protection Society and our hospital), Australia and a qualitative systematic review.
RESULTS: We identified 88 negligent and 43 non-negligent sterilization failures. Filshie and ring methods failed earlier than diathermy and Pomeroy methods. Sterilization failure occurred significantly earlier in negligent than non-negligent failure mechanisms [median failure intervals 7.0 versus 12.0 months; Hazard ratio (2.35 95% CI 1.314.21)]. Knowing that sterilization failure occurred early, increased the probability that the failure mechanism was likely to be negligent rather than non-negligent.
CONCLUSIONS: A short interval to failure is suggestive of a negligent failure mechanism. There is less certainty in the predictive value of longer time intervals on the mechanism of failure due to a paucity of cases. A national register of failed sterilizations that have been systematically investigated is needed to improve our understanding of negligent and non-negligent failure mechanisms.
Key words: sterilization/tubal/treatment failure/survival analysis/Bayes theorem
Submitted on June 6, 2007; resubmitted on April 24, 2007; accepted on May 24, 2007.